Index: bin/cat/cat.c
===================================================================
--- bin/cat/cat.c
+++ bin/cat/cat.c
@@ -155,7 +155,7 @@
 		err(EXIT_FAILURE, "unable to create Casper");
 
 	fa = fileargs_cinit(casper, argc, argv, O_RDONLY, 0,
-	    cap_rights_init(&rights, CAP_READ | CAP_FSTAT | CAP_FCNTL),
+	    cap_rights_init(&rights, CAP_READ | CAP_FSTAT | CAP_FCNTL | CAP_SEEK),
 	    FA_OPEN | FA_REALPATH);
 	if (fa == NULL)
 		err(EXIT_FAILURE, "unable to create fileargs");
Index: contrib/capsicum-test/copy_file_range.cc
===================================================================
--- /dev/null
+++ contrib/capsicum-test/copy_file_range.cc
@@ -0,0 +1,159 @@
+#include <sys/types.h>
+#include <fcntl.h>
+
+#include <string>
+
+#include "capsicum.h"
+#include "capsicum-test.h"
+#include "syscalls.h"
+
+#define TOPDIR "cap_copy_file_range"
+#define INFILE "infile"
+#define OUTFILE "outfile"
+
+/* Test that copy_file_range() checks capabilities correctly.
+ * When used without offset arguments, copy_file_range() should
+ * require only CAP_READ on the source and CAP_WRITE on the destination
+ * file descriptors, respectively.
+ * When used with offset arguments, copy_file_range() should
+ * additionally require CAP_SEEK.
+ */
+class CopyFileRangeTest : public ::testing::Test {
+ public:
+  CopyFileRangeTest() {
+    int rc = mkdir(TmpFile(TOPDIR), 0755);
+    EXPECT_OK(rc);
+    if (rc < 0) {
+      EXPECT_EQ(EEXIST, errno);
+    }
+    wd_ = open(TmpFile(TOPDIR), O_DIRECTORY);
+    EXPECT_OK(wd_);
+    CreateFile(TmpFile(TOPDIR "/" INFILE));
+    CreateFile(TmpFile(TOPDIR "/" OUTFILE));
+  }
+  ~CopyFileRangeTest() {
+    close(wd_);
+    unlink(TmpFile(TOPDIR "/" INFILE));
+    unlink(TmpFile(TOPDIR "/" OUTFILE));
+    rmdir(TmpFile(TOPDIR));
+  }
+
+ private:
+  void CreateFile(const char *filename) {
+    int fd = open(filename, O_CREAT|O_RDWR, 0644);
+    const char *contents = "lorem ipsum dolor sit amet";
+    EXPECT_OK(fd);
+    for (int i = 0; i < 100; i++) {
+      EXPECT_OK(write(fd, contents, strlen(contents)));
+    }
+    close(fd);
+  }
+
+ protected:
+  int wd_;
+
+  int openInFile(cap_rights_t *rights) {
+    int fd = openat(wd_, INFILE, O_RDONLY);
+    EXPECT_OK(fd);
+    EXPECT_OK(cap_rights_limit(fd, rights));
+    return fd;
+  }
+  int openOutFile(cap_rights_t *rights) {
+    int fd = openat(wd_, OUTFILE, O_WRONLY);
+    EXPECT_OK(fd);
+    EXPECT_OK(cap_rights_limit(fd, rights));
+    return fd;
+  }
+};
+
+TEST_F(CopyFileRangeTest, ReadWrite) {
+  cap_rights_t rights_in, rights_out;
+
+  cap_rights_init(&rights_in, CAP_READ);
+  cap_rights_init(&rights_out, CAP_WRITE);
+
+  int fd_in = openInFile(&rights_in);
+  int fd_out = openOutFile(&rights_out);
+  off_t off_in = 0, off_out = 0;
+
+  EXPECT_OK(copy_file_range(fd_in, NULL, fd_out, NULL, 8, 0));
+  EXPECT_NOTCAPABLE(copy_file_range(fd_in, &off_in, fd_out, NULL, 8, 0));
+  EXPECT_NOTCAPABLE(copy_file_range(fd_in, NULL, fd_out, &off_out, 8, 0));
+  EXPECT_NOTCAPABLE(copy_file_range(fd_in, &off_in, fd_out, &off_out, 8, 0));
+  off_in = 20;
+  off_out = 20;
+  EXPECT_NOTCAPABLE(copy_file_range(fd_in, &off_in, fd_out, NULL, 8, 0));
+  EXPECT_NOTCAPABLE(copy_file_range(fd_in, NULL, fd_out, &off_out, 8, 0));
+  EXPECT_NOTCAPABLE(copy_file_range(fd_in, &off_in, fd_out, &off_out, 8, 0));
+  close(fd_in);
+  close(fd_out);
+}
+
+TEST_F(CopyFileRangeTest, ReadSeekWrite) {
+  cap_rights_t rights_in, rights_out;
+
+  cap_rights_init(&rights_in, CAP_READ, CAP_SEEK);
+  cap_rights_init(&rights_out, CAP_WRITE);
+
+  int fd_in = openInFile(&rights_in);
+  int fd_out = openOutFile(&rights_out);
+  off_t off_in = 0, off_out = 0;
+
+  EXPECT_OK(copy_file_range(fd_in, NULL, fd_out, NULL, 8, 0));
+  EXPECT_OK(copy_file_range(fd_in, &off_in, fd_out, NULL, 8, 0));
+  EXPECT_NOTCAPABLE(copy_file_range(fd_in, NULL, fd_out, &off_out, 8, 0));
+  EXPECT_NOTCAPABLE(copy_file_range(fd_in, &off_in, fd_out, &off_out, 8, 0));
+  off_in = 20;
+  off_out = 20;
+  EXPECT_OK(copy_file_range(fd_in, &off_in, fd_out, NULL, 8, 0));
+  EXPECT_NOTCAPABLE(copy_file_range(fd_in, NULL, fd_out, &off_out, 8, 0));
+  EXPECT_NOTCAPABLE(copy_file_range(fd_in, &off_in, fd_out, &off_out, 8, 0));
+  close(fd_in);
+  close(fd_out);
+}
+
+TEST_F(CopyFileRangeTest, ReadWriteSeek) {
+  cap_rights_t rights_in, rights_out;
+
+  cap_rights_init(&rights_in, CAP_READ);
+  cap_rights_init(&rights_out, CAP_WRITE, CAP_SEEK);
+
+  int fd_in = openInFile(&rights_in);
+  int fd_out = openOutFile(&rights_out);
+  off_t off_in = 0, off_out = 0;
+
+  EXPECT_OK(copy_file_range(fd_in, NULL, fd_out, NULL, 8, 0));
+  EXPECT_OK(copy_file_range(fd_in, NULL, fd_out, &off_out, 8, 0));
+  EXPECT_NOTCAPABLE(copy_file_range(fd_in, &off_in, fd_out, NULL, 8, 0));
+  EXPECT_NOTCAPABLE(copy_file_range(fd_in, &off_in, fd_out, &off_out, 8, 0));
+  off_in = 20;
+  off_out = 20;
+  EXPECT_OK(copy_file_range(fd_in, NULL, fd_out, &off_out, 8, 0));
+  EXPECT_NOTCAPABLE(copy_file_range(fd_in, &off_in, fd_out, NULL, 8, 0));
+  EXPECT_NOTCAPABLE(copy_file_range(fd_in, &off_in, fd_out, &off_out, 8, 0));
+  close(fd_in);
+  close(fd_out);
+}
+
+TEST_F(CopyFileRangeTest, ReadSeekWriteSeek) {
+  cap_rights_t rights_in, rights_out;
+
+  cap_rights_init(&rights_in, CAP_READ, CAP_SEEK);
+  cap_rights_init(&rights_out, CAP_WRITE, CAP_SEEK);
+
+  int fd_in = openInFile(&rights_in);
+  int fd_out = openOutFile(&rights_out);
+  off_t off_in = 0, off_out = 0;
+
+  EXPECT_OK(copy_file_range(fd_in, NULL, fd_out, NULL, 8, 0));
+  EXPECT_OK(copy_file_range(fd_in, &off_in, fd_out, NULL, 8, 0));
+  EXPECT_OK(copy_file_range(fd_in, NULL, fd_out, &off_out, 8, 0));
+  EXPECT_OK(copy_file_range(fd_in, &off_in, fd_out, &off_out, 8, 0));
+  off_in = 20;
+  off_out = 20;
+  EXPECT_OK(copy_file_range(fd_in, NULL, fd_out, &off_out, 8, 0));
+  EXPECT_OK(copy_file_range(fd_in, &off_in, fd_out, NULL, 8, 0));
+  EXPECT_OK(copy_file_range(fd_in, &off_in, fd_out, &off_out, 8, 0));
+  close(fd_in);
+  close(fd_out);
+}
Index: contrib/capsicum-test/makefile
===================================================================
--- contrib/capsicum-test/makefile
+++ contrib/capsicum-test/makefile
@@ -1,5 +1,5 @@
 all: capsicum-test smoketest mini-me mini-me.noexec mini-me.setuid $(EXTRA_PROGS)
-OBJECTS=capsicum-test-main.o capsicum-test.o capability-fd.o fexecve.o procdesc.o capmode.o fcntl.o ioctl.o openat.o sysctl.o select.o mqueue.o socket.o sctp.o capability-fd-pair.o linux.o overhead.o rename.o
+OBJECTS=capsicum-test-main.o capsicum-test.o capability-fd.o copy_file_range.o fexecve.o procdesc.o capmode.o fcntl.o ioctl.o openat.o sysctl.o select.o mqueue.o socket.o sctp.o capability-fd-pair.o linux.o overhead.o rename.o
 
 GTEST_DIR=gtest-1.10.0
 GTEST_INCS=-I$(GTEST_DIR)/include -I$(GTEST_DIR)
Index: sys/kern/vfs_syscalls.c
===================================================================
--- sys/kern/vfs_syscalls.c
+++ sys/kern/vfs_syscalls.c
@@ -4879,6 +4879,7 @@
 	size_t retlen;
 	void *rl_rcookie, *rl_wcookie;
 	off_t savinoff, savoutoff;
+	cap_rights_t *incap, *outcap;
 
 	infp = outfp = NULL;
 	rl_rcookie = rl_wcookie = NULL;
@@ -4898,8 +4899,16 @@
 		 */
 		len = SSIZE_MAX;
 
+	incap = &cap_read_rights;
+	if (inoffp != NULL) {
+		incap = &cap_pread_rights;
+	}
+	outcap = &cap_write_rights;
+	if (outoffp != NULL) {
+		outcap = &cap_pwrite_rights;
+	}
 	/* Get the file structures for the file descriptors. */
-	error = fget_read(td, infd, &cap_read_rights, &infp);
+	error = fget_read(td, infd, incap, &infp);
 	if (error != 0)
 		goto out;
 	if (infp->f_ops == &badfileops) {
@@ -4910,7 +4919,7 @@
 		error = EINVAL;
 		goto out;
 	}
-	error = fget_write(td, outfd, &cap_write_rights, &outfp);
+	error = fget_write(td, outfd, outcap, &outfp);
 	if (error != 0)
 		goto out;
 	if (outfp->f_ops == &badfileops) {